on_hover_text/ui many times will stack tooltips beneath the previous

CHANGELOG.md

@@ -29,6 +29,7 @@ The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/).
 * Changed default font to [Ubuntu-Light](https://fonts.google.com/specimen/Ubuntu).
 * Remove minimum button width
 * Refactored `egui::Layout` substantially, changing its interface.
+* Calling ``on_hover_text`/`on_hover_ui` multiple times will stack tooltips underneath the previous ones.
 
 ### Removed 🔥
 

egui/src/containers/popup.rs

@@ -4,12 +4,22 @@ use crate::*;
 
 /// Show a tooltip at the current mouse position (if any).
 pub fn show_tooltip(ctx: &Arc<Context>, add_contents: impl FnOnce(&mut Ui)) {
-    if let Some(mouse_pos) = ctx.input().mouse.pos {
-        //  TODO: default size
-        let id = Id::tooltip();
-        let window_pos = mouse_pos + vec2(16.0, 16.0);
-        show_popup(ctx, id, window_pos, add_contents);
-    }
+    let tooltip_rect = ctx.memory().tooltip_rect;
+
+    let window_pos = if let Some(tooltip_rect) = tooltip_rect {
+        tooltip_rect.left_bottom()
+    } else if let Some(mouse_pos) = ctx.input().mouse.pos {
+        mouse_pos + vec2(16.0, 16.0)
+    } else {
+        return; // No good place for a tooltip :(
+    };
+
+    //  TODO: default size
+    let id = Id::tooltip();
+    let response = show_popup(ctx, id, window_pos, add_contents);
+
+    let tooltip_rect = tooltip_rect.unwrap_or_else(Rect::nothing);
+    ctx.memory().tooltip_rect = Some(tooltip_rect.union(response.rect));
 }
 
 /// Show a tooltip at the current mouse position (if any).

egui/src/memory.rs

@@ -54,6 +54,12 @@ pub struct Memory {
     #[cfg_attr(feature = "serde", serde(skip))]
     popup: Option<Id>,
 
+    /// If a tooltip has been shown this frame, where was it?
+    /// This is used to prevent multiple tooltips to cover each other.
+    /// Initialized to `None` at the start of each frame.
+    #[cfg_attr(feature = "serde", serde(skip))]
+    pub(crate) tooltip_rect: Option<Rect>,
+
     /// Useful for debugging, benchmarking etc.
     pub all_collpasing_are_open: bool,
     /// Useful for debugging, benchmarking etc.
@@ -162,6 +168,7 @@ impl Memory {
     ) {
         self.used_ids.clear();
         self.interaction.begin_frame(prev_input, new_input);
+        self.tooltip_rect = None;
 
         if !prev_input.mouse.down {
             self.window_interaction = None;

egui/src/types.rs

@@ -116,7 +116,8 @@ impl std::fmt::Debug for Response {
 }
 
 impl Response {
-    /// Show this UI if the item was hovered (i.e. a tooltip)
+    /// Show this UI if the item was hovered (i.e. a tooltip).
+    /// If you call this multiple times the tooltips will stack underneath the previous ones.
     pub fn on_hover_ui(self, add_contents: impl FnOnce(&mut Ui)) -> Self {
         if self.hovered {
             crate::containers::show_tooltip(&self.ctx, add_contents);
@@ -124,7 +125,8 @@ impl Response {
         self
     }
 
-    /// Show this text if the item was hovered (i.e. a tooltip)
+    /// Show this text if the item was hovered (i.e. a tooltip).
+    /// If you call this multiple times the tooltips will stack underneath the previous ones.
     pub fn on_hover_text(self, text: impl Into<String>) -> Self {
         self.on_hover_ui(|ui| {
             ui.add(crate::widgets::Label::new(text));

egui/src/widgets/drag_value.rs

@@ -146,7 +146,7 @@ impl<'a> Widget for DragValue<'a> {
                 .sense(Sense::click_and_drag())
                 .text_style(TextStyle::Monospace);
             let response = ui.add(button);
-            // response.on_hover_text("Drag to edit, click to enter a value"); // TODO: may clash with users own tooltips
+            let response = response.on_hover_text("Drag to edit, click to enter a value");
             if response.clicked {
                 ui.memory().request_kb_focus(kb_edit_id);
                 ui.memory().temp_edit_string = None; // Filled in next frame